Sales Blanket Order - fully invoice at start?

Hi all,
What's the best method to fully invoice a Sales Order and then create multiple shipments as required by customer to fulfil the order in NAV?
I've had a look at the Sales Blanket order functionality which seems to be best suited for the task but not too sure about the invoicing process as I believe it's only possible invoice what's shipped/called off from the blanket order?
What I have in mind is to create a Sales Order for the full quantity and amount, ship all to a special location (non-reservable, zero value) and fully invoice the customer. For each call off transfer stock from this location and reserve against the Sales Order, only charging delivery + storage charges and the item line with quantity shipped and 100% discount.
Is there a slicker or better way to handle this?
Many thanks!